O-Desmethylvenlafaxine succinate is a novel salt form of isolated major active metabolite of venlafaxine and has been shown to inhibit norepinephrine and serotonin uptake. O-Desmethylvenlafaxine chemically named as 1-[2-(dimethylamino)-1-(4-phenopethyl]cyclohexanol having the following structure

U.S. Pat. No. 4,535,186 patent is filed on Oct. 26, 1983, this application has been granted on Aug. 13, 1985 and assigned to American Home Products corporation. In this application, process for the preparation of Desmethylvenlafaxine is disclosed and claimed, wherein 1-[1-(4-benzyloxyphenyl)-2-(dimethylamino)ethyl]cyclohexanol is subjected to hydrogenation reaction in the presence of 10% Palladium carbon followed by workup to give O-Desmethylvenlafaxine, which is further converted to fumarate salts by conventional methods.
In U.S. Pat. No. 6,673,838 patent application claimed different polymorphic forms of O-Desmethylvenlafaxine succinate and discloses the process for the preparation of Form-I, II, III, IV and amorphous.
Venlafaxine base is used as starting material in the preparation of O-Desmethylvenlafaxine, as demonstrated in U.S. Pat. No. 6,689,912, U.S. Pat. No. 6,197,828 WO 03/048104 and US 2005/0197392.
We have carried out the crystallization of O-Desmethylvenlafaxine succinate in a different solvents, mixture of solvents and applying different parameters to obtain a novel process for the preparation of O-Desmethylvenlafaxine succinate polymorphic Forms.